Javascript 使用OverlappingMarkerSpider获取可蜘蛛化标记的数量

我目前正在我的项目中使用OverlappingMarkersPiderFire。 我想显示一个spiderfiable标记下的元素数量，就像GoogleMapsAPI中的集群一样

我实现的代码如下所示：

google.maps.event.addListener(marker, 'spider_format', function(status) {   

        if(status == OverlappingMarkerSpiderfier.markerStatus.SPIDERFIED 
|| status == OverlappingMarkerSpiderfier.markerStatus.UNSPIDERFIABLE)

        {
            marker.setIcon('Markers/marker.png'); 
//use a regular marker if the element is already spiderfied or if it can not be spiderfied
        }

        if(status == OverlappingMarkerSpiderfier.markerStatus.SPIDERFIABLE)

        {
            marker.setIcon('Markers/cluster_marker.png'); //use a cluster marker
            // get the number of elements under the cluster....
            // show the number of elements under the cluster....
        }           
    });       

有没有办法获得每个spiderfiable标记下要spiderfied的元素数